Laget de laa



(No Model.)

J. SOHLMAN. DYNAMO ELECTRIC MACHINE.

No. 597,090. Patented Jan. 11,1898.

\NVENTEIFQ Aftl 5 UNITED STATES PATENT OFFICE.

JOHANNES SOIILMAN, OF WIBORG, FINLAND, ASSIGNOR TO THE AKTIEBO- LAGET DE LAVALS ANGTURBIN, OF STOOKI'IOLM, SXVEDEN.

DYNAMO-ELECTRIC MACHlNE,

SPECIFICATION forming part of Letters IPatent No. 597,090, dated January 11, 1898. Application filed May 22, 1897. Serial No. 637,785. (No model.) Patented in Sweden September 14:, 1895, No. 7,322-

To ctZZ whom it may concern:

Be it known that I, J OHANNES SOHLMAN,

a subject of the Emperor of Russia, and a resident of \Viborg, in the Grand Duchy of Finland, have made certain new and useful Improvements in Dynamo-Electric Machines, of Which the following is a specification.

The invention has been patented in Sweden, No. 7,322, dated September 14, 1895.

The present invention has for its object an improvement in alternating-current generators of that kind in which the stationary part of the magnetic field consists of an iron casin g provided with inward-projecting pole- 15 pieces surrounded by induction-coils.

The improvement consists in an arrangement by means of which the magnetic spreading is reduced to a minimum and the induction action upon the magnetizing-coils is obviated,

although such coils are placed in the intermediate proximity of the induction-coils.

On the accompanying drawing is shown the front View of a machine provided with the present improvement.

A indicates the iron casing, which may be formed of layers of sheet-iron or of such layers partly and solid partly.

n a and s s are the pole-pieces carried by the casing and projecting inwardly. I are the induction-coils surrounding these polepieces.

B indicates a rotating iron core placed centrally in the casing A and formed of layers of sheet-iron. Said core B has no coils, but is 3 5 provided with projections Z), preferably in a number less by half than the number of polepieces in the casing A.

Now the improvement consists therein that every two adjacent pole-pieces n n and s s in the casing A are surrounded by a common exciting-coil M in such a way that one such pair of pole-pieces receives northern magnetism,

the following pair southern, and so on, when a continuous current is running through the coils M. The projections 19 of the iron core B being sufficiently broad (preferably double the size of the stationary pole-pieces n n and s 8) no magnetic variations arise Within the exciting-coil M of two adjacent pole-pieces with the same polarity during the rotation of the core On the contrary the magnetism in the induction-coils belonging to these poles is submitted to rapid variations. \Vhile the magnetism in the stationary pole-pieces in the machine varies between nearly 0 and a maximum, the magnetism is reversed in the rotating core. In the outer casing the magnetism is partly constant and partly varying.

In those parts which are situated between a north pole and a south pole the magnetism is constant. These parts may therefore be formed solid.

Having now particularly described my invention and ascertained in what manner the same is to be carried out, I declare that what I claim as my invention is In an alternating-current generator the combination with an even number of stationary pairs of pole-pieces, projecting radially from a casing, each pole-piece surrounded by an induction-coil, while every two of said pole-pieces are surrounded by an excitingcoil, of a rotating core, placed centrally in the casing and arranged in such a manner in relation to the pole-piece, that the magnetism is fully reversed in the core during its rotation.

In witness whereof I have hereunto set my hand in presence of two witnesses.

JOHANNES SOHLMAN.

Witnesses:

ARTE. LITJEBLAD, R. E. WINTER. 

